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A high electric field was applied cyclically to poly(vinylidene fluoride) films, during which the simultaneous and time-resolved measurements of the two-dimensional wide-angle X-ray diffraction (WA...

We investigate fluorescent defect centers in 4H silicon carbide p–n junction diodes fabricated via aluminum-ion implantation into an n-type bulk substrate without the use of an epitaxial growth process. At room temperature, electron-irradiated p–n junction diodes exhibit electroluminescence originating from silicon-vacancy defects. For a diode exposed to an electron dose of $$1 \times 10^{18}\,{{\mathrm{cm}}}^{-2}$$ 1 × 10 18 cm - 2 at $$800\,{{\mathrm{keV}}}$$ 800 keV , the electroluminescence intensity of these defects is most prominent within a wavelength range of 400–$$1100\,{{\mathrm{nm}}}$$ 1100 nm . The commonly observed $${{\mathrm{D}}}_1$$ D 1 emission was sufficiently suppressed in the electroluminescence spectra of all the fabricated diodes, while it was detected in the photoluminescence measurements. The photoluminescence spectra also displayed emission lines from silicon-vacancy defects.

Solid films of deoxyribonucleic acid (DNA) containing a hydrated ionic liquid, choline dihydrogen phosphate (CDP), were prepared by a solvent-casting method. Thermal properties, aggregation structure, thermal molecular motion, and tensile properties of CDP-containing DNA films were examined by thermogravimetry (TG), wide-angle X-ray diffraction (WAXD) measurement, dynamic mechanical analysis (DMA), and tensile tests, respectively. The water retentivity of the films at room temperature was much improved with CDP. The packing density of DNA helical chains clearly depended on the amount of CDP in the film. A small amount of CDP contributed to the suppression of the BI → BII conformational transition and the cooperative motion of the DNA duplex in the film. The tensile properties of the film drastically changed in the presence of CDP. When the amount of hydrated CDP in the film increased, the mechanical response of the film changed from glassy-like to rubbery-like via a semicrystalline-like state. The above results make it clear that CDP plays two major roles as a water absorber and plasticizer in the DNA film. Thus, it can be concluded that the use of an ionic liquid as an additive significantly increases the possibility of using a DNA solid film as a structural material.

In this study, we evaluated the mechanical properties of pre-consumer recycled polypropylene thin films molded at more various temperatures, times and cooling conditions. We also evaluated the durability toward UV irradiation, and the effects of re-molding and annealing on the stability of these improved mechanical properties. The results of this study show that the mechanical properties of recycled polypropylene can be greatly improved to be almost the same as those of virgin polypropylene by choosing suitable molding condition. The mechanically improved samples also show enhanced durability towards UV. Annealing is also carried out to stabilize the mechanical properties that had been improved by quenching.

We synthesized side-chain crystalline block copolymer that exhibit an adsorptive interaction with polyethylene (PE) using a monomer with a long alkane side chain and a hydrophilic monomer. By coating PE with a dilute solution of these block copolymers, the PE surface can easily be endowed with hydrophilicity in a uniform manner. This method does not require a special experimental apparatus or reagents and is more viable than conventional methods in terms of energy efficiency and cost, which means it has a lower environmental impact. Based on the measured contact angle on the modified PE surface, we also evaluated the effects of copolymer concentration in the coating solution and the degree of polymerization in the functional region of the copolymer. The results suggest that the hydrophilicity of the PE surface can be controlled by adjusting these parameters. We synthesized side-chain crystalline block copolymer that exhibit an adsorptive interaction with polyethylene (PE) using a monomer with a long alkane side chain and a hydrophilic monomer. By coating PE with a dilute solution of these block copolymers, the PE surface can easily be endowed with hydrophilicity in a uniform manner. This method does not require a special experimental apparatus or reagents and is more viable than conventional methods in terms of energy efficiency and cost, which means it has a lower environmental impact. Based on the measured contact angle on the modified PE surface, we also evaluated the effects of copolymer concentration in the coating solution and the degree of polymerization in the functional region of the copolymer. The results suggest that the hydrophilicity of the PE surface can be controlled by adjusting these parameters.

In recent years, real-time observations of molecules have been required to understand their behavior and function. To date, we have reported two different time-resolved observation methods: diffracted x-ray tracking and diffracted x-ray blinking (DXB). The former monitors the motion of diffracted spots derived from nanocrystals labeled onto target molecules, and the latter measures the fluctuation of the diffraction intensity that is highly correlated with the target molecular motion. However, these reports use a synchrotron x-ray source because of its high average flux, resulting in a high time resolution. Here, we used a laboratory x-ray source and DXB to measure the internal molecular dynamics of three different systems. The samples studied were bovine serum albumin (BSA) pinned onto a substrate, antifreeze protein (AFP) crystallized as a single crystal, and poly{2-(perfluorooctyl)ethyl acrylate} (PC8FA) polymer between polyimide sheets. It was found that not only BSA but also AFP and PC8FA molecules move in the systems. In addition, the molecular motion of AFP molecules was observed to increase with decreasing temperature. The rotational diffusion coefficients (DR) of BSA, AFP, and PC8FA were estimated to be 0.73 pm2/s, 0.65 pm2/s, and 3.29 pm2/s, respectively. Surprisingly, the DR of the PC8FA polymer was found to be the highest among the three samples. This is the first report that measures the molecular motion of a single protein crystal and polymer by using DXB with a laboratory x-ray source. This technique can be applied to any kind of crystal and crystalline polymer and provides atomic-order molecular information.

The reverse martensitic transformation proceeds through several sub-processes at various length and time scales. We study the transformation kinetics at the high thermodynamic driving force regime, by inducing a rapid heating-pulse in a shape memory alloy wire. We track the evolution of the transformation at the microsecond scale by multi-frame time-resolved X-ray diffraction at synchrotron radiation with simultaneous high-bandwidth force measurements. The x-ray probed a narrow region at the periphery of the wire, while the force was a measure for the transformation-induced stress in the bulk of the wire. We reveal three stages occurring at different times and length-scales in the material. During the first 5 μs the transformation is undetectable. Then, a rapid transformation occurs near the surface and saturates after 9 μs. The evolution of the transformation in the bulk becomes discernible only after the transformation near the surface completes and lasts for approximately 40 μs.

Stimuli-responsive materials are promising intelligent materials because of precise and easy control of their various properties simply by providing external stimuli. Herein, we developed a temperature-responsive thermal rheological (TR) fluid, consisting of a solution of polyethylene (PE) fine particle dispersion and a side-chain crystalline block copolymer (SCCBC). The viscosity of the TR fluid was reduced significantly depending on the degree of polymerization of SCCBC; the viscosity was minimized by using a stearyl acrylate15-n-butyl acrylate59 (STA15-nBA59) which has a low total molecular weight and whose functional unit has larger molecular weight than the side-chain crystalline unit. In addition, the TR fluids changed from liquid to almost-solid state, depending on temperature, and the transition temperature of TR fluid was increased using SCCBC with a higher total molecular weight. This result implied that the transition temperatures and viscosity of the TR fluids could be controlled simply by changing the molecular weight of SCCBCs.

Previous structural analyses have shown that R2R3, the minimum unit of the DNA-binding domain of the transcriptional factor c-Myb, is largely flexible in solution, and changes to a more rigid structure upon DNA binding. In this study, we evaluated the structural dynamics using the diffracted X-ray tracking method, in correlation with DNA-binding abilities under different salt conditions, and compared them with the previous results. The resultant curve of the mean square angular displacements (MSD) clearly showed that the flexibility of R2R3 was decreased upon DNA binding, and the DNA-binding energies determined using the angular diffusion coefficients were in good agreement with those determined using isothermal titration calorimetry. The results of the MSD curves also indicate that the translational length reduces by approximately half upon DNA binding.

Previously, we demonstrated the ATP-dependent dynamics of a group II chaperonin at the single-molecule level by diffracted X-ray tracking (DXT). The disadvantage of DXT is that it requires a strong X-ray source and also perfect gold nano-crystals. To resolve this problem, we developed diffracted electron tracking (DET). Electron beams have scattering cross-sections that are approximately 1000 times larger than those of X-rays. Thus, DET enables us to perform super-accurate measurements of the time-resolved 3D motion of proteins labeled with commercially available gold nanorods using a scanning electron microscope. In this study, we compared DXT and DET using the group II chaperonin from Methanococcus maripaludis (MmCpn) as a model protein. In DET, the samples are prepared in an environmental cell (EC). To reduce the electron beam-induced protein damage, we immobilized MmCpn on the bottom of the EC to expose gold nanorods close to the carbon thin film. The sample setup worked well, and the motions of gold nanorods were clearly traced. Compared with the results of DXT, the mobility in DET was significantly higher, which is probably due to the difference in the method for immobilization. In DET, MmCpn was immobilized on a film of triacetyl cellulose. Whereas proteins are directly attached on the surface of solid support in DXT. Therefore, MmCpn could move relatively freely in DET. DET will be a state-of-the-art technology for analyzing protein dynamics.

Summary Recently, we found that Side Chain Crystalline Block Co-Polymer (SCCBC), which has a long alkane side chain (>C10), can be used as a good dispersant for a concentrated polyethylene fine-particle dispersion. We also found that the viscosity of this concentrated dispersion increased at high temperature and returned to normal at low temperature. We named this fluid Thermal Rheological Fluid (TR Fluid). The mechanism of this phenomenon involves the attachment and detachment of SCCBC. With the use of this mechanism, we examined whether it could be possible to modify the properties of a polyethylene (PE) surface. A PE film was dipped in a dilute SCCBC solution, and its surface was coated by SCCBC. The water contact angle changed from around 90° before coating to around 70° after coating. Thus, the surface of PE was made more hydrophilic. The adhesion strength was examined by a tensile test. The PE film elongated before the attached region broke. These results showed that SCCBC has a very high adhesion strength and can be used as a surface modifier or primer for attachment. Additionally, SCCBC could be easily removed from the PE film by hot water, and thus, it should be very easy to recycle or re-use the PE.

Recently, we polymerized a block copolymer that was constructed of side-chain crystalline monomer and a solvent-compatible monomer, which we referred to as a side-chain crystalline block copolymer (SCCBC). This SCCBC has a specific melting point. We found that this SCCBC was adsorbed onto polyethylene (PE) crystal by via supramolecular interaction. In addition, through this supramolecular interaction, the SCCBC acts as a dispersant for a concentrated PE particle dispersion, and this dispersion can be considered a Thermal Rheological Fluid. By using this novel supramolecular interaction, we can easily modify the surface properties of high crystalline polymers (PE, polytetrafluoroethylene (PTFE), etc.), which have been thought to be inert. Especially, we can modify the inner surface properties of porous membranes without using physical methods (such as UV irradiation or plasma irradiation). Furthermore, these modified surface properties can revert to those in the non-modified state under changes in temperature. It may possible to develop intelligent materials with use of this supramolecular interaction in the near future. [doi:10.2320/matertrans.MF201318] (Received March 18, 2013; Accepted April 25, 2013; Published May 31, 2013)

This study aimed to clarify the morphological characteristics of the fused portion in the mandibular fused deciduous anterior teeth using microfocus x-ray computerized tomography, a method which allows nondestructive three-dimensional observation at high resolution in any direction. The specimens consisted of five mandibular deciduous central/lateral incisor fused teeth, and four lateral incisor/canine fused teeth. These specimens were scanned using x-ray micro-CT and three-dimensional images of anatomical features of the crowns were reconstructed. Two-dimensional sliced images were created and then, the morphology of the fused portions were examined by measuring angle of the fused portion, enamel and dentin thickness at the fused portion. Angles of lingual fused portion in deciduous central/lateral incisor fused teeth, and labial fused portion in deciduous lateral incisor/canine fused teeth are significantly smaller, and the enamel thickness at these fused portions are also thinner. The values of the dentin thickness in deciduous central/lateral incisors tended to be thinner than those of deciduous canine, which means dentin thickness of the deciduous central/lateral incisors are thinner than that of canine. The fused portions in the fused deciduous anterior teeth have the similar morphological features to those of pit and fissure of the occlusal surface in molars and are likely to be the initiation and predilection sites of dental caries. Therefore, it is considered to be preferable to apply pit and fissure sealant into the fused portions at an early time point of the treatment.

We evaluated commercially available, portable, on-site equipment for chemical warfare agent detection (a gas detection tube, ion mobility spectrometer, surface acoustic wavelength detector, flame photometric detector, photoionization detector, Fourier-transformed infrared spectrometer and a gas chromatograph-mass spectrometer) using authentic, vaporized chemical-warfare agents from the standpoint of their qualitative detection characteristics, detection limits, response times, frequency of false alarms and residubility on the devices. False alarms and the strong adsorption of agents by the devices are typical drawbacks of such equipment. As a screening method for biological warfare agents, on-site methods using flow cytometry, bioluminescence assay, and lateral flow immunoassay were developed.

Effect of sensitivity improvement of Near Infrared: NIR digital cameras on Normalized Difference Vegetation Index: NDVI measurements in particular for agricultural field monitoring is clarified. Comparative study is conducted between sensitivity improved visible to near infrared camera of CuInGaSe: CIGS and the conventional camera. Signal to Noise: S/N ratio and sensitivity are evaluated with NIR camera data which are acquired in tea farm areas and rice paddy fields. From the experimental results, it is found that S/N ratio of the conventional digital camera with NIR wavelength coverage is better than CIGS utilized image sensor while the sensitivity of the CIGS image sensor is much superior to that of the conventional camera. Also, it is found that NDVI derived from the CIGS image sensor is much better than that from the conventional camera due to the fact that the sensitivity of the CIGS image sensor in red color wavelength region is much better than that of the conventional camera.

Recycled plastics are considered to have less-desirable mechanical properties and durability than virgin materials, and this is usually thought to be due to chemical degradation. However, we recently found that pre-consumer polypropylene (Pre-RPP) was not chemically degraded and had almost the same molecular properties as virgin polypropylene (VPP). In this study, we subjected recycled pre-consumer polypropylene to various thermal treatments and found that we could obtain properties similar to those of virgin polypropylene. We also investigated the fracture surfaces by SEM. The results showed that the mechanical properties were closely related to the inner structure, and if we can control the inner structure of Pre-RPP we may be able to improve its mechanical properties and durability so that they are almost the same as those of VPP.

A simplified prediction model of the equiaxed crystal ratio (ECR) in continuously cast slabs of ferritic stainless steel was investigated based on the columnar to equiaxed transition (CET) model proposed by J. D. Hunt. The present model assumes that CET occurs when a parameter G/V1/2 at a solid fraction of 0.3 is smaller than a critical value, CET. This model can explain comparatively well the effects of the casting speed, melt superheat, steel composition, intensity and position of the electromagnetic stirring (EMS), and secondary cooling intensity on measured ECR. The calculated results also show that an optimum EMS position and casting speed for maximizing ECR exist. Moreover, it was found that there is a proportional relationship between the best-fit values of CET and N01/3C01/2 calculated from measured data. This means that the simplified Hunt model is applicable to predict ECR in continuously cast slabs. The mechanism by which equiaxed crystal bands are generated is also discussed in relation to the behavior of G/V1/2.

Recently, high power laser diodes (LDs) are appling the laser material processing. In this report, we have presented a brief overview of high power laser diode, and describe the basic technology of high power laser diodes and system for pumping solid state laser and direct applications.

Thermal behavior was examined using DSC and TG for the samples prepared by dissolving LiClO4 in several polyoxyethylene/polyethylenimine (PEO/PEI) blends (7/3–9.5/0.5 by repeat units) along with their lithium ion conductivity. Concerning the matrix polymers, while the pristine PEO and PEI began to thermally decompose at 185 and 230 °C, respectively, the (8/2) PEO/PEI blend had lost only 6.5% of its weight before 300 °C was reached. Dissolution of LiClO4 made the systems thermally even more robust: [(8/2) PEO/PEI]10–LiClO4 suffered practically no weight loss below 300 °C. So far [(8/2) PEO/PEI]10–LiClO4 has been our best-behaving SPE (σ=2.2×10−4 S cm−1 at 77 °C and 2.5×10−6 S cm−1 at 30 °C): it is less conductive than a previously reported PEO12–LiClO4 by a factor of 2.2 at 77 °C, but its conductivity drop due to the matrix crystallization below 65 °C is considerably milder and the conductivity at 30 °C was ca. 100 times higher than the plain PEO–LiClO4 systems. A significant effect of the residual methanol on the ionic conductivity of our [(8/2) PEO/PEI]10–LiClO4 samples was recognized, which necessitated our previously reported log σ vs. 1000/T curve to be corrected downward by ca. half an order of magnitude.

Fiber lasers are promising for industrial applications because they excel in beam quality, efficiency, compactness, and ruggedness. However, even in the double-clad geometry, the power scalability is severely limited with the end-pumping technique. Indeed, the end faces of an optical fiber offer only a small area and this makes it difficult to launch the pump light from the many high power diode lasers. To solve this pump source multiplexing problem we researched and developed the fiber laser in original which was called “Fiber structure type fiber laser”. The disk-shaped, fiber-structure type fiber laser that we developed provides an average output of 1 kW (total output at both ends) and a laser efficiency (electric-to-optical) of 15.6 %. As the fiber laser except for the bundled type, the average output 1 kW is the highest value as long as we know.

In order to use an atomic force microscope to measure the intramolecular mechanics of a single protein or polymer molecule, the very initial stage of stretching must be recorded without complications from nonspecific adhesions of target molecules to substrate materials. Although polyethylene glycol itself shows a certain level of adhesion to the functionalized surface of crystalline silicon wafer used as a substrate, adhesion of polypeptides and proteins can be minimized by covering the substrate surface with flexible polyethylene glycol chains. Determination of the cantilever spring constant is also important in the quantitative analysis of the result of force measurements. We introduce a hydrodynamic method of cantilever calibration as an effective method of estimating the relative spring constant of the cantilever. Finally, for mechanical manipulation of DNA, we introduce the use of a positively charged glass surface to keep DNA molecules in the stretched conformation for molecular manipulation including mechanical cutting of stretched DNA.

Y. Matsushita, H. Sekiguchi, C. Jae Wong, M. Nishijima, K. Ikezaki, D. Hamada, Y. Goto & Y. C. Sasaki "Nanoscale Dynamics of Protein Assembly Networks in Supersaturated Solutions", Scientific Reports, Volume 7, Article number: 13883, Springer Nature, 2017, Proteins in solution are conventionally considered macromolecules. Dynamic microscopic structures in supersaturated protein solutions have received increasing attention in the study of protein crystallisation and the formation of misfolded aggregates. Here, we present a method for observing rotational dynamic structures that can detect the interaction of nanoscale lysozyme protein networks via diffracted X-ray tracking (DXT). Our DXT analysis demonstrated that the rearrangement behaviours of lysozyme networks or clusters, which are driven by local density and concentration fluctuations, generate force fields on the femtonewton to attonewton (fN – aN) scale. This quantitative parameter was previously observed in our experiments on supersaturated inorganic solutions. This commonality provides a way to clarify the solution structures of a variety of supersaturated solutions as well as to control nucleation and crystallisation in supersaturated solutions.

Picosecond time-resolved X-ray diffraction has been used to study the nanoscale thermal transportation dynamics of bare gold nanocrystals and thiol-based self-assembled monolayer (SAM)-coated integrated gold nanocrystals on a SiO2glass substrate. A temporal lattice expansion of 0.30–0.33% was observed in the bare and SAM-coated nanocrystals on the glass substrate; the thermal energy inside the gold nanocrystals was transported to the contacted substrate through the gold–SiO2interface. The interfacial thermal conductivity between the single-layered gold nanocrystal film and the SiO2substrate is estimated to be 45 MW m−2 K−1from the decay of the Au 111 peak shift, which was linearly dependent on the transient temperature. For the SAM-coated gold nanocrystals, the thermal dissipation was faster than that of the bare gold nanocrystal film. The thermal flow from the nanocrystals to the SAM-coated molecules promotes heat dissipation from the laser-heated SAM-coated gold nanocrystals. The thermal transportation of the laser-heated SAM-coated gold nanocrystal film was analyzed using the bidirectional thermal dissipation model.

In search of more viable solid polymer matrices for lithium ion conductors, solid solutions of LiClO4 in polyoxyethylene/polyethylenimine (PEO/PEI) (8:2, 5:5, and 2:8 by repeat units) blends were examined. In the 8:2 blends, conductivities increased with the decrease in the salt content. Conductivities in the 8:2- and the pure PEO systems were comparable at temperatures higher than 350 K. The drastic conductivity drop due to crystallization known for the PEO systems did not occur in the 8:2 systems; the 8:2 systems became ca. three orders of magnitude more conductive at room temperature. In contrast, the 5:5 systems suffered a severe conductivity drop near 330 K. The abrupt conductivity drop disappeared again in the 2:8 systems. They were more conductive than the pure PEI systems. Weak temperature dependence of conductivity made their room temperature condutivities even higher than those for the pure PEO systems.

Kilowatt-class fiber lasers are reviewed. From the early days, fiber lasers have been studied to make use of the high pump intensity resulting from light confinement in the fiber core. In a conventional fiber laser, the pump light is coupled through the fiber core end section. This section is too small to launch a high power diode pump beam. This limits the output power to several tens of mW. The double-clad structure allows us to increase the output power by several orders of magnitude but it can hardly exceed of a few tens of W. A new concept called “fiber embedded fiber laser” or“free shape laser” will again increase the maximum output power, making kW fiber lasers a reality. In this paper, this new concept is presented and compared with usual fiber laser technology.

Diffracted X-Ray tracking (DXT) method has been developed for obtaining dynamical information at single protein molecule level. The motion of an individual single gold nanocrystal can be observed by this method, which is linked to specific site in the molecule, using a time resolved Laue diffraction technique. This method needs a very strong X-ray source, so we continue to develop a compact instrument with use of the electron beam instead of the X-ray. The Electron Back-Scattered Diffraction (EBSD) is adopted to monitor the Three-dimensional (3D) crystal orientation of the gold nanocrystal. We call this the Diffracted Electron Tracking (DET). For this purpose, we have developed the wet cell using the very thin carbon sealing film for maintained atmospheric pressure from high vacuum surroundings of a scanning electron microscope (SEM), and confirmed that the EBSD pattern (EBSP) can be obtained from the gold nanocrystals through the carbon sealing film of the wet cell. When the gold nanocrystal moved by the motion of labeled molecules, the change of the EBSP is observed. Moreover, we confirmed EBSP can be obtained from 40nm diameter of commercial colloidal gold instead of gold nanocrystal. The colloidal gold was more sensitive and more accurate to detect the motion of linked molecule by reason of its good sphericity and well-regulated particle size. Recently, we developed new configuration of the wet cell that might be able to obtain EBSP without intensive electron damages. This method may contribute to develop as a single molecular technology for fragile molecules by electron irradiation. using this method, we are planning to detect rotational motion of the chaperonin protein in the presence of ATP.

Single crystals of K 2 ZnI 4 with monoclinic Sr 2 GeS 4 structure prepared by the Bridgman method were investigated through DTA and dielectric measurements. Ferroelectric activity was found below 270 K, where the b -direction dielectric constant showed a sharp peak. The spontaneous polarization measured by the pyroelectric charge method was 0.32 µ C/cm 2 at 100 K. The dielectric constant also showed a small stepwise anomaly around 190 K.